Lifting equipment



J. M. EITEL LIFTING EQUIPMENT Sept. 25, 1962 Filed Jan. 23, 1956 TIE- l 3 Sheets-Sheet 1 INVENTOR.

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Sept. 25, 1962 J. M. EITEL 3,

LIFTING EQUIPMENT Filed Jan. 25, 1956 3 Sheets-Sheet 2 Y Jw M. E/TEL ATTDRNE /s,

Sept, 25, 1962 J. M. ElTEL LIFTING EQUIPMENT 3 Sheets-Sheet 3 Filed Jan. 23, 1956 E Q .m. MI

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INVENTOR. Jnv M. E/TEL flTTORNEVS Qm m Patented s ept. 25, 1962 3,055,459 LIFTING EQUIPMENT Jay M. Eitel, Los Altos, Calif., assignor to Los Altos Engineering (10., Redwood City, Calif, a partnership Filed Jan. 23, 1956, Ser. No. 560,621 Claims. (Cl. 189-41) This invention relates generally to lifting equipment. More particularly it relates to the type of lifting equipment wherein the load supporting structure is rotatable about a vertical axis and includes a boom structure pivotally mounted on said load supporting structure for vertical swinging movement about a horizontal axis.

In operating lifting equipment of this type, certain safety apparatus should be incorporated in the equipment to prevent serious injury to operating personnel and to the equipment. In the past, equipment of this type has been practically devoid of any safety apparatus.

In general, it is an object of the present invention to provide an improved lifting equipment that is safe to operate.

Another object of the invention is to provide lifting equipment of the above character with safety measures for lowering the boom structure to prevent the boom structure from crashing to the ground in the event of failure of the operating means for raising and lowering the boom structure.

Another object of the invention is to provide control means for de-energizing the operating means for raising and lowering the boom structure when the boom structure fails to lower in a normal manner.

Additional objects of the invention will appear from the following description in which the preferred embodiment has been set forth in detail in conjunction with the accompanying drawing.

Referring to the drawing:

FIGURE 1 is a side elevational view of a lifting equipment incorporating the present invention.

FIGURE 2 is an enlarged cross sectional view showing the load supporting structure.

FIGURE 3 is an enlarged cross sectional view taken along the line 3-3 of FIGURE 2 and shows in particular the safety means for lowering the boom structure.

FIGURE 4 is an enlarged cross sectional view of the valve assembly used in the safety means for lowering the boom structure.

FIGURE 5 is an enlarged detail view of the safety control means for disrupting the power supply for the operating means for raising and lowering the boom structure.

FIGURE 6 is a cross sectional view illustrating another embodiment of a dash pot for use in safety means for lowering the boom structure.

FIGURE 7 is an enlarged detail view with certain portions broken away showing the extensible boom structure and the means for extending the boom structure.

FIGURE 8 is a cross sectional view taken along the line 8-8 of FIGURE 7.

FIGURE 9 is an enlarged detail view with certain parts broken away of the gearmotor for raising and lowering the boom.

FIGURE 10 is an enlarged cross sectional view taken along the line lit-10 of FIGURE 9.

FIGURE 11 is an enlarged cross sectional view taken along the line 11-11 of FIGURE 9.

;In general, the present invention consists of lifting equipment in which safety means for lowering the boom structure has been providedto prevent the boom structure from crashing to the ground in the event of failure of the operating means for raising and lowering the boom structure. The lifting equipment has also been provided with safety control apparatus which is responsive to slack in an elongate element operatively connected to the boom structure and serves to disrupt the power supply for the motive means used for raising and lowering the boom structure when this slack condition exists. Whenever the boom structure fails to lower in a normal manner, the safety control means prevents further lowering until the abnormal condition is corrected.

The lifting equipment illustrated in the drawing has been mounted on a self propelled vehicle 11 having front and rear wheels 12 and 13 and a framework 14 mounted upon the wheels as described in my co-pending app1ication Serial Number 560,622, filed January 23, 1956, now Patent No. 2,841,404, patented July 1, 1958. However, if desired the lifting equipment can be mounted on a platform, skids or the like.

The lifting equipment is mounted so that it can be rotated about a vertical axis. One means found to be suitable for such mounting consists of a vertical stud shaft 16 having its lower end fixed to the framework 14 in a region generally overlying the rear wheels 13. The load supporting structure 17 is rotatably mounted on stud shaft 16 and is adapted to be rotated about the vertical axis formed by the stud shaft.

The load supporting structure consists of a cab 18 which is open at the rear and at the top and has its bottom wall or floor journalled on stud shaft 16. Suitable means is provided for rotating the load supporting structure about the stud shaft. Such means can consist of gearing 19 mounted on the floor of the cab and driving a pinion 21 which engages a large ring gear 22 fixed to the framework 14-. It is apparent that as the gearing 19 is driven by the reversible motor 23 through the belt 24 that the cab 18 will be rotated in'either a clockwise or counterclockwise direction about a vertical axis depending upondirection of rotation of the motor 23.

A boom structure 26 is pivotally mounted upon a pivot pin 27 carried by the upper portion of the side walls of the cab 18 so that the boom structure may be swung about a horizontal axis. Suitable operating means is provided for raising or lowering the boom or in other words for swinging the boom about the horizontal axis provided by pivot pin 27. Such operating means can consist of motive means such as a gearmotor 28 and an elongate element such as a chain or cable operatively connected between the gearmotor 28 and the boom structure 26. The gearmotor 28 and the cab 18 are carried by an angular framework 31 that is fixed to a hub 32 rotatably mounted on the upper portion of stud shaft 16. Gearmotor 28 is secured to the angular framework by a bolt 33 that is threaded into a mounting bracket 34. The bracket 34 thus serves to tightly clamp the gearmotor to the framework 31. Y

Gearmotor 28 is provided with a sprocket (not shown) which is adapted to engage the elongate element or chain 29 to move it in one direction or the other depending upon the direction of rotation of the gearmotor. As shown in the drawing, one end of the chain 29 extends into gearmotor 28 and the other end of the chain is fastened to an extension 36 of the boom structure 26. The chain is reeved or passed over a sprocket wheel 37 so that the portion of the chain between the sprocket wheel 37 and the gearmotor 28 lies in the same general line regardless of the position of the boom structure and the remainder of the chain. Sprocket wheel 37 is carried between two diagonal members 38 mounted Within the cab. A mechanical advantage is obtained by passing the chain over another sprocket wheel 39 rotatably mounted on extension 36 and a sprocket wheel 41 mounted between the diagonal members 38.

As shown in FIGURES 9, 10 and 11, suitable means such as a self energizing brake 42 is provided in the gearmotor for maintaining the boom structure in a predetermined position about the horizontal axis when the gearmotor 28 is de-energized. As is well known to those skilled in the art such a brake can consist of a wheel or drum 43 mounted on the armature shaft 44. A brake band 46 encircles the drum and is provided with a suitable brake lining 47. The brake band 46 is urged towards a self energizing or a drum engaging position by spring means consisting of a pair of springs 49 mounted on a bolt 51. The brake band is adapted to be moved to a disengaged position by solenoid operated means 54. The solenoid opera-ted means consists of a solenoid 56 which is adapted to rotate a shaft 57 through a linkage 58. One end of the shaft 57 is journalled in a framework 59 and the other end is journalled in the housing of the gearmotor. The end of the shaft 57 within the housing has a rectangular portion 5721 which extends between bolts 61 mounted on the upper ends of the brake band 46. The stroke of the solenoid 56 is such that shaft 57 is rotated through approximately 90 degrees. Thus, when the solenoid is energized, portion 57a is rotated counterclockwise as viewed in FIGURE 11 until it has urged the bolts 61 sufficiently far apart to disengage the brake band 46 from the brake drum 43. When the solenoid is deenergized, the springs 49 urge the brake band into engagement with the brake drum 43. Thus, as soon as the boom structure 26 has been raised or lowered a desired amount, the gearmotor 28 and the solenoid 56 are de-energized and the springs 49 urge the brake band 46 into engagement with the brake drum to prevent the boom structure from dropping.

The boom structure 26 consists of a main section 66 and a telescopic section 67. The telescopic section 67 is carried in a telescoping relation within the main section 66. The main section is provided with a plurality of rollers 68 of various sizes to facilitate movement of the telescoping boom axially of the main section 66. The telescoping section is also provided with rollers 69 of various sizes to facilitate this axial movement. Suitable means is provided for moving the telescopic section axially of the main section and can consist of a gearmotor 71 mounted on the main section 66 and driving a sprocket 72. Sprocket 72 engages a drive chain 73 which passes over another SPIOCACL wheel 74 mounted on a shaft 76 that is journalled in one side of the main section 66. One end of the chain 73 is fastened to the telescoping section at 77 and the other end of the chain is also fastened to the telescoping section at 78.

It is apparent that by operation of the gearmotor 71 the boom structure may be lengthened or shortened by extending or retracting the telescoping section 67. Suitable brake means is provided in the gearmotor 71 similar to that described for gearmotor 28 to prevent rotation of the gearmotor when the gearmotor is de-energized and thus serves to hold the telescoping section in any desired position.

The work cage 81 is pivotally mounted on the outer end of the telescoping section 67 and is provided with a control mechanism 82 as described in my co-pending application Serial :Number 579,689, filed April 20, 1956, now Patent No. 2,841,659, patented July 1, 1958, whereby any one of the motor 23 or the gearmotors 28 and 71 may be operated individually or simultaneously to rotate the work cage 81 about a vertical axis, raise or lower the boom structure or axially extend and retract the boom structure. Suitable control means (not shown) may also be provided in the cab 18 so that the position of the work cage can be controlled from the ground.

Suitable safety lowering means is provided for lowering the boom structure 26 at a controlled rate in the event of failure of the operative means for raising and lowering the boom structure. Such means can consist of a pair of dash pots 86 and 87. Each dash pot is comprised of a cylindrical member 88 that has its lower end pivotally mounted on lugs 89 mounted on a framework 91. Framework 91 is fixed to the side walls of the cab 18. A piston-like member 92 is mounted in each of the cylindrical members and is movable axially of the cylindrical member by a piston rod 93. The piston rods of both dash pots are pivotally connected to arms 94 mounted on the sides of the main section of the boom structure 26. The lower ends of the cylindrical members are connected by piping 96 and 97 to a T 98. The T is connected to a valve assembly 99 by coupling 101.

The valve assembly 99 consists of a body 102 having aligned flow passages 103 and 104 which are connected by orifices 106 and 107. The flow through port 106 is adapted to be metered or restricted by a needle valve assembly 108. The needle valve assembly is comprised of a valve member 109 which is threaded into the body 102 and a packing nut '111 fixed to the valve body. An O-ring 112 within a counterbored recess in the body forms a seal between the packing nut and the body. It is apparent that the flow of fluid through orifice 106 can be controlled by rotation of valve member 109 for a purpose hereinafter described. Orifice 107 is adapted to be closed by a check valve 113 and consists of a ball 114 which is continuously urged into orifice 107 by a spring 116. Spring 116 is retained within the body 102 by a nut 117 threaded into the body. It is apparent that the check valve 113 will prevent the flow of fluid from passage 103 to passage 104 and that it will permit the flow of fluid from passage 104 to passage 103 for a purpose hereinafter described.

The valve assembly 99 is connected to piping 119 by coupling 121. Piping 119 is connected to a cross 122. The cross is connected to the upper end of dash pot 86 and is also connected to the upper end of dash pot 87 by a flexible tubing 123. The cross is also connected by flexible tubing 126 to a surge tank 124 mounted in the main section of the boom.

The pistons 92 each have a bleed orifice 92a which serves to eliminate air pockets which may occur in the fluid.

Operation of the safety lowering means may now be described as follows: Let it be assumed that the boom structure 26 is in the position shown in FIGURE 2 and that a failure occurs in the operative means for raising and lowering the boom structure such as for example the breaking of the elongate element or chain 29. Instead of crashing to the ground, the boom structure will be lowered at a controlled rate by the dash pots 86 and 87. It is apparent that the rate of lowering is determined by the needle valve 108 because the fluid must be displaced -from the lower portion of the cylinders 88 and must pass through the piping 96 and 97 into the valve assembly 99 through flow passage 103, orifice 106, flow passage 104 into piping 119 and then into the upper portions of the cylinders 88. The check valve 113 effectively prevents any flow of fluid in this direction through orifice 107. The quantity of fluid passing through bleed orifices 92a in the pistons is relatively small with respect to the amount of fluid passing through orifices 106. Thus, it is apparent that the rate of lowering of the boom structure can be definitely controlled by adjustment of the needle valve 108. For a purpose hereinafter described, the rate of lowering must be slightly greater than the rate at which the boom structure is normally lowered by the operative means for raising and lowering the boom structure.

Since the fluid displaced from both dash pots must pass through a single needle valve, it is apparent that the load of the boom structure will be equally distributed between both dash pots. 'At the pistons 92 move into the cylinders 8 8, the fluid which cannot enter the upper portions of the cylinders 88 because of the space occupied by the piston rods 93 is forced into the surge tank 124.

When the boom structure 26 is raised by the operative means, fluid is sucked back into the space provided as the pistons are raised in the cylinders. In this case, the flow through valve assembly 99 is reversed and the fluid passes from passage 104 into passage 103 through both orifices operative means.

In the drawing I have shown a pair of dash pots 36 and 87 for lowering the boom structure. However, if desired, a single dash pot may be utilized for lowering the boom structure. Other improvements and modifications may be made within the scope of the present invention. For example, as shown in FIGURE 6, other types of lowering means may be utilized in place of the dash pots 86 and 87. The dash pot shown in FIGURE 6 consists of members 131 and 132 movable relative to each other. Member 131 is in the form of an open ended cylinder and is secured to a plate-like member 91a by suitable resilient means such as a pad or grommet 13 3 which is mounted in an opening in the member 91a. The pad 133 can be of any suitable resilient material such as neoprene. A rod 134 is connected to the bottom wall of the cylindrical member 132 and extends through the resilient pad and is clamped on the other side of member 91a by a washer 135 and a nut 136 mounted on the rod.

Member 132 is also in the form of a hollow cylindrical member and is adapted to be moved longitudinally within the cylindrical member 131. The bottom wall of member 132 is provided with orifices 137 and 138 and bleed orifice 141. The flow of fluid through orifice 137 is controlled by a needle valve assembly .13 9 whereas the flow through orifice 138 is controlled by a check valve assembly 140. Needle valve assembly 139 consists of an open ended cylindrical housing 142 having its open end threaded into the bottom wall of member 132 and overlying opening 137. A valve member 143 is threaded into the housing and is adapted to restrict the flow of fluid through opening 137. An operating stem 144 is connected to the valve member and extends through the top wall of the member 1 32. An opening 146 in the housing 142 allows fluid to pass into and out of the housing.

The check valve 140 consists of a ball 147 which is continuously urged into the orifice 138 by spring 148. The spring 148 is held in place by an insert 149 threaded onto the lower wall of the member 132. The insert 149 is provided with an aperture 145 for passage of fluid. An opening 151 is provided in the upper wall of member 132 to admit air into the chamber within member 1 32.

vSuitable sealing means is provided between member 182 and member 131 and consists of an annular ring 152 threaded on member 131 and carrying an O-ring 153 which engages the side walls of the member 132.

It is apparent that the fluid device shown in FIGURE 6 operates in a manner very similar to the dash pots 86 and 87, however, in this instance all external piping has been eliminated, and no surge tank or reservoir is required.

Assuming that the device shown in FIGURE 6 is connected to the boom structure, it is apparent that the device will also serve to control the rate of lowering of the boom structure. As the boom structure is lowered, member 132 will be moved downwardly into member 13 1. The rate of movement will be controlled by the flow of fluid through needle valve 137.

Upon raising of the boom structure by the operative means, the check valve will serve to permit substantially unrestricted flow of fluid from member 132 into member 131.

If it is desired to use two of the dash pots shown in FIGURE 6 for lowering a single boom structure, it is necessary to provide means for determining when the load is evenly distributed between both dash pots. This can be done by measuring the deflection of the pad 133 and adjusting both needle valves 139 until the deflection in both pads is substantially the same.

Suitable safety control means responsive to slack in the elongate element or chain 29 is provided to disrupt the power supply for the motive means or gearmotor 28. Such control means consists of an operating lever 156 pivotally mounted on bracket 34. One end of the operating lever is provided with an operating member or foot 157 which is adapted to engage a portion of the elongate element 29 at a point between sprocket 37 and the gearmotor 28. It is apparent that a portion of the elongate element is always traveling along the line between sprocket 37 and gearmotor 28 regardless of the position of the boom structure 26.

The operating lever 156 is continuously urged against the elongate element 29 by suitable means such as a spring 158 having one end connected to the operating member or lever at 159 and having the other end connected to bracket 34 at 161. A switch 162 is mounted on the framework 91 and is connected in series with the electrical circuit for energizing and de-energizing the gearmotor 28. A bolt 163 is threaded into the operating lever 156 and is adjustable with respect to the operating lever 156 axially of the bolt. The bolt 163 is adapted to engage the switch 162 to operate the same.

The operating lever 156 is adapted to be moved between first and second positions by the spring 158. The operating lever 156 is in the first position when the chain or elongate element 29 is taut as shown in FIGURE 5. In this position of the operating lever the switch 162 is not operated. When the element moves to a slack position as'shown by the dotted lines in FIGURE 5, the operating lever 156 is moved to the second position in which it serves to operate switch 162. Operation of switch 162 serves to disrupt or de-energize the gearmotor 28.

Thus, it is apparent that when the boom structure fails to lower in a normal manner such as when the boom structure comes in contact with an object the elongate element will slacken. Upon slackening of the elongate element, the operating lever 156 will be moved to operate switch 162 to de-energize the gearmotor 23 to prevent further operation of the gearmotor 2 8 until the element again becomes taut. It will then be necessary for the operator to determine what has arrested the downward movement of the boom structure and correct the same before the boom structure can be lowered to the desired position.

It is apparent that the flow of fluid through the orifices 106 associated with the dash pots 86 and 87 must be great enough so that the dash pots 86 and 87 will not arrest the downward movement of the boom structure during a normal lowering operation by the operative means for raising and lowering the boom structure. If the needle valves 108 are not properly adjusted to pro- .vide such flow, the dash pots 86 and 87 would tend to arrest the downward movement of the boom structure control means would operate switch 162 to de-energize gearmotor 28. Gearmotor 28 would remain de-energized until the boom structure had been lowered suflicien-tly by the dash pots 86 and '37 to again tighten the chain after which the gearmotor would take over lowering of the boom structure until the dash pots 86 and 87 again arrested the downward movement of the boom structure. This is objectionable because it would cause more or less jerky downward movement and undue wear of the associated parts. Hence, needle valves 1% must be adjusted so that the dash pots 36 and 87 will not retard the normal downward movement of the boom structure.

The equipment is foolprof in that if the needle valve is moved to a completely open position, the boom structure still would not drop too rapidly in the event of failure of the operative means. The bleed orifice and the orifice for the needle valve are properly sized to prevent such an occurrence. The needle valve is provided instead of an orifice of the proper size so that adjustment can be made for viscosity changes in the fluid under diiferent temperature conditions.

It is apparent from the foregoing that I have provided lifting equipment in which several safety devices have been provided to reduce the possibility of injury to operating personnel and damage to the lifting equipment. The safety lowering apparatus definitely prevents the boom and work cage from crashing to the ground in case of failure of the operative means for raising and lowering the boom structure. The safety control means is responsive to any slack in the elongate element for raising and lowering the boom and serves to disrupt the power supply for the motive means whenever anything serves to arrest the normal downward movement of the boom structure.

I claim:

1. In lifting equipment, a framework, a lift supporting structure carried by the framework, a boom structure pivotally mounted on said lift supporting structure for swinging movement about a horizontal axis, mechanical operating means for raising and lowering said boom structure including an elongate element which is taken in and payed out as the boom is raised and lowered, said mechanical operating means also including motive means for taking in and paying out said elongate element, and control means responsive to slack in said elongate element to disrupt the power supply for said motive means.

2. In lifting equipment, a framework, a lift supporting srtucture carried by the framework, a boom structure pivotally mounted on said hoist supporting structure for swinging movement about a horizontal axis, mechanical operating means including an elongate element, a rotatable member and motive means for taking in and paying out said elongate element, said elongate element being reeved over said rotatable member and one end of said element being connected to said boo-m structure whereby as the element is taken in and payed out said boom structure will be raised or lowered about said horizontal axis, control means including a switch operating member adapted to be moved between first and second positions, means for continuously urging said operating member into engagement with the portion of the elongate element between the rotatable member and the motive means, said operating member being in the first position when said elongate member is taut and being in the second position when said elongate element is slack, and switch means operated by said operating member when said operating member is moved to the second position to disrupt the power supply for said motive means.

3. In lifting equipment, a framework, a lift supporting structure carried by the framework, a boom structure pivotally mounted on said lift supporting structure for swinging movement about a horizontal axis, mechanical operating means for raising and lowering the boom structure about said horizontal axis including an elongate element which is taken in and payed out as the boom is raised and lowered, said operating means also including motive means for taking in and paying out said elements, safety control means responsive to slack in said element to disrupt the power supply for said motive means, said operating means also including brake means for preventing movement of said motive means upon interruption of the power supply for said motive means, safety lowering means of the displacement type comprising members forming a fluid containing space to which fluid is supplied or displaced when the members are moved relative to each other, said members being connected to said boom structure and said lift supporting structure, adjustable orifice means for restricting the fiow of fluid fro-m said space to cause the lowering of the boom structure at a controlled rate in the event of failure of said operating means, said orifice means being adjusted to lower said boom structure at a rate greater than the boom structure is lowered by said mechanical operating means, and check valve means adapted to be opened by fluid suction in said space to admit fluid thereto during raising of the boom structure by said operating means.

4. In lifting equipment, a framework, a lift supporting structure carried by the framework, a boom structure pivotally mounted on said lift supporting structure for swinging movement about a horizontal axis, operative means connected to said boom structure for raising and lowering the boom structure about the horizontal axis, safety lowering means of the displacement type comprising a pair of dash pots mounted on opposite sides of the boom structure, each of said dash pots consisting of piston and cylinder members pivotally connected to the boom structure at a point removed from the horizontal axis and pivotally connected to the lift supporting structure below the horizontal axis, said members defining a space to which the fluid is supplied or displaced, orifice means connected to the space in each of said dash pots to cause lowering of the boom structure at a controlled rate in the event of failure of the operative means, said orifice means serving to distribute the weight of the boom structure equally between said dash pots, said controlled rate of lowering being at a rate greater than the rate of lowering by said operative means.

5. ln lifting equipment, a framework, a lift supporting structure carried by the framework, a boom structure pivotally mounted on said lift supporting structure for swinging movement about a horizontal axis, mechanical operating means for raising and lowering the boom structure about said horizontal axis including an elongate element which is taken in and payed out as the boom structure is raise and lowered, said operating means also including motive means for taking in and paying out said element, and safety control means responsive to slack in said element to interrupt the power supply for said motive means, said operating means also including brake means for preventing movement of said motive means upon interruption of the power supply for said motive means, and safety means in continuous operation for lowering said boom structure at a uniform controlled rate in the event of failure of said operative means, said controlled rate of lowering being greater than the rate of lowering by said mechanical operating means to prevent the formation of slack in said element during normal operation of said lifting equipment.

References Cited in the file of this patent UNITED STATES PATENTS 1,160,976 Myers Nov. 16, 1915 2,196,511 Wagner et al. Apr. 9, 1940 2,376,019 Thomas May 15, 1945 2,509,686 Huston May 30, 1950 2,627,560 Eitel Feb. 3, 1953 2,627,985 Sathre et al Feb. 10, 1953 2,730,245 Auld Jan. 10, 1956 

